INTERESTING INSECTS

By N A Martin (2010, revised 2017)

Hook-tip fern looper

Gargaphia muriferata Walker 1863

Drepanodes muriferata (Walker 1863)

Panagra ephyraria Walker, 1863

Zanclopteryx cookaria Felder & Rogenhofer, 1875

Zanclopteryx haastaria Felder & Rogenhofer, 1875

Drepanodes neoselena Meyrick, 1909

Gargaphia neoselena (Meyrick, 1909)

This endemic moth is found throughout New Zealand where its two native host plants, leather-leaf fern, Pyrrosia eleagnifolia and hound’s tongue fern, Microsorum pustulatum (Polypodiaceae) occur. It is present in cities and native ecosystems.

Conservation status: Widespread, not threatened.

The moth and caterpillars are found all year round.

The wings of the moths are about 25 mm long and are hooked at the tips. Coloration is very variable. Male moths are dark reddish brown. A dark diagonal line runs across the forewing and hindwing. Sometimes the line is reduced to a series of dots. Sometimes wings are dark brown in front of this line and light brown behind the line. There are two tiny white dots in the middle of the forewing, one above the other and sometimes surrounded by brown scaling. Female moths tend to be greyer than males, often a purplish grey. They also have a stouter abdomen.

Eggs and caterpillar

Eggs are laid singly or in small groups, in rows in crannies presumably near a host plant. The eggs are white when first laid then turn red. Later the caterpillar can be seen through the eggshell.

Tiny looper caterpillars hatch from eggs and feed by chewing on the fronds. The caterpillars grow by changing skins (moulting). Like a typical looper caterpillar, it has three pairs of legs by its head and two pairs of ‘prolegs’ (false legs) at its rear end. The caterpillar walks by looping along. It first brings its rear end up towards its front and holds on with its prolegs. Then it stretches forwards and holds on with its true legs while it again brings its rear end forwards, repeating the process.

Caterpillar appearance and camouflage

The mature caterpillar is about 30 mm long and brown with long broken stripes that make it look like the debris found amongst the ferns. The caterpillar may rest stretched out on the underside of a frond or ‘stand up’ at an angle to look like a stick. During the day, the caterpillars hide amongst the debris at the base of fronds or amongst leaf litter. If caterpillars are disturbed, they jump from the fern, twisting and coiling, dropping to the ground and disappearing into the litter. The caterpillars have a very long modified seta (hair) that, when touched, triggers the jumping and coiling response.

Caterpillars eat by chewing the edge of fern fronds. They excrete brown droppings (frass). The presence of fresh droppings is a sign that caterpillars are present.

Cocoon and pupa

When the caterpillar is fully grown, it goes into the litter and makes a loose silk-lined cocoon. The caterpillar moults into a pupa that has a long hook at its rear end which holds the pupal skin in the cocoon when the moth emerges from the pupa.

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of a pinned male moth. Creator: Birgit E Rhode. © Landcare Research. [Image: 3KP]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of a pinned female moth. Creator: Birgit E Rhode. © Landcare Research. [Image: 3KO]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of dead moth. Creator: Tim Holmes. © Plant & Food Research. [Image: 3KL]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), underside of dead moth. Creator: Tim Holmes. © Plant & Food Research. [Image: 3KK]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of moth. Creator: Tim Holmes. © Plant & Food Research. [Image: 15UX]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), underside of moth. Creator: Tim Holmes. © Plant & Food Research. [Image: 15UZ]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of hounds tongue fern, Microsorum pustulatum. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V0]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of hounds tongue fern, Microsorum pustulatum. © Plant & Food Research. [Image: 15V4]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of hounds tongue fern, Microsorum pustulatum. Creator: Tim Holmes. © Plant & Food Research. [Image: 15UU]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of leather-leaf fern, Pyrrosia eleagnifolia. Creator: Tim Holmes. © Plant & Food Research. [Image: 3KG]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), showing its three pairs of true legs (right) and two pairs of ‘prolegs’ (left). Creator: Tim Holmes. © Plant & Food Research. [Image: 3KH]

Pupa of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), removed from its silk-lined cocoon. Creator: Tim Holmes. © Plant & Food Research. [Image: 3KM]

Pupa of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), removed from its silk-lined cocoon; note the long hook at its rear (narrow) end. Creator: Tim Holmes. © Plant & Food Research. [Image: 3KN]

Pupa of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), showing the hooks at its rear (narrow) end that catch on silk cocoon during adult moth emergence. Creator: Tim Holmes. © Plant & Food Research. [Image: 15UW]

The moth may be found near its host plants. It may be recognised by the hook-tip forewings (longer than any other moth species) and the pair of tiny white dots in the middle of the forewings.

This is the only looper caterpillar known on leather-leaf fern, Pyrrosia eleagnifolia. However, two species of looper caterpillar may be found on hound’s tongue fern, Microsorum pustulatum. Hook-tip fern looper, Sarisa muriferata, wriggles vigorously when disturbed, whereas the caterpillars of the angled fern looper, Ischalis nelsonaria (Felder & Rogenhofer, 1875) are sluggish. They are also brown, but are coated in brown fur.

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of a pinned male moth. Creator: Birgit E Rhode. © Landcare Research. [Image: 3KQ]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of moth. Creator: Tim Holmes. © Plant & Food Research. [Image: 15UX]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of a pinned male moth. Creator: Birgit E Rhode. © Landcare Research. [Image: 3KP]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upper side of a pinned female moth. Creator: Birgit E Rhode. © Landcare Research. [Image: 3KO]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of hounds tongue fern, Microsorum pustulatum. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V1]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of hounds tongue fern, Microsorum pustulatum. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V3]

Hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), caterpillar. Creator: Tim Holmes. © Plant & Food Research. [Image: 3KF]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of leather-leaf fern, Pyrrosia eleagnifolia. Creator: Tim Holmes. © Plant & Food Research. [Image: 3KG]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of leather-leaf fern, Pyrrosia eleagnifolia. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 28ET]

No pathogens or predators of this moth have been reported. However, birds and spiders are likely to prey on the moths and insect may prey on the caterpillars.

The caterpillars have special setae (hairs) on their abdomen, which when touched, trigger a defensive response; the larva immediately drops from the fern, twisting its body vigorously. This behaviour allows it to descend easily through leaf litter and escape predators.

Parasitoids

One larval parasitoid, Aleiodes declanae (Hymenoptera: Braconidae), has been found and reared. The adult wasp lays an egg in the small caterpillar. When the caterpillar has partly grown and the wasp larva is fully grown, the caterpillar holds on to the plant at its head end and the body sticks straight out. The wasp pupates inside the dead caterpillar skin. When it is ready to emerge, the adult wasp chews a hole in the tail end of the caterpillar skin.

Dead caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), killed by parasitoid larva, Aleiodes declanae (Hymenoptera: Braconidae), and ‘glued’ by its head end to the leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V5]

Dead caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), killed by parasitoid larva, Aleiodes declanae (Hymenoptera: Braconidae), and ‘glued’ by its head end to the leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V6]

Dead caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), killed by parasitoid larva, Aleiodes declanae (Hymenoptera: Braconidae), and ‘glued’ by its head end to the leaf. The wasp pupated inside the skin of the caterpillar. Round exit hole of wasp at tail end of caterpillar skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V7]

Dead caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), killed by parasitoid larva, Aleiodes declanae (Hymenoptera: Braconidae), and ‘glued’ by its head end to the leaf. The wasp pupated inside the skin of the caterpillar. Round exit hole of wasp at tail end of caterpillar skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V8]

Adult wasp, Aleiodes declanae (Hymenoptera: Braconidae), whose larva is a parasitoid of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), caterpillars. Creator: Tim Holmes. © Plant & Food Research. [Image: 15V9]

Underside of an adult wasp, Aleiodes declanae (Hymenoptera: Braconidae), whose larva is a parasitoid of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), caterpillars. Creator: Tim Holmes. © Plant & Food Research. [Image: 15VE]

Adult wasp, Aleiodes declanae (Hymenoptera: Braconidae), whose larva is a parasitoid of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), caterpillars. Creator: Tim Holmes. © Plant & Food Research. [Image: 15VA]

The moth has two host plants, the endemic species leather-leaf fern, Pyrrosia eleagnifolia (Bory) Hovenkamp and the native hound’s tongue fern, Microsorum pustulatum (G. Forst.) Copel. Both fern species are in the family Polypodiaceae and have leathery fronds.

The caterpillars chew the fronds from the edge. The damage is not diagnostic of the species.

Fronds of leather-leaf fern, Pyrrosia eleagnifolia, showing chewing made by caterpillars of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), upperside of frond. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 3KE]

Fronds of leather-leaf fern, Pyrrosia eleagnifolia, showing chewing made by caterpillars of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), underside of frond. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 3KD]

Caterpillar of the hook-tip fern looper, Sarisa muriferata, (Lepidoptera: Geometridae), on a frond of hound's tongue fern, Microsorum pustulatum. Creator: Tim Holmes. © Plant & Food Research. [Image: 15UV]

Crowe A 2004. Life-size guide to New Zealand ferns. Albany, Auckland, New Zealand, Penguin Group (NZ). 32 p.

Hoare R. 2014. A photographic guide to moths & butterflies of New Zealand. New Holland Publishers (NZ) Ltd, Auckland, New Zealand. Pp. 1-143.

Wientraub JD, Scoble MJ 2004. Lithinini (Insecta: Lepidoptera: Geometridae: Ennominae). Fauna of New Zealand 49: 1-48.

Robert Hoare for information about the moth.

The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.

Landcare Research New Zealand Limited (Landcare Research) for permission to use photographs.

1 September 2017. NA Martin. Natural enemies, parasitoid name given and defensive behaviour added. New Information Source added.

5 June 2015. NA Martin. Synonyms added. Annual cycle: added photographs of moths, larva and pupa. Recognition: added photos of moths and larvae. Natural enemies: rewritten and photographs added.

19 May 2011. NA Martin. Annual cycle: added photos of moths, larva and pupa; Recognition: added photos of moths and larvae; Host plants: added photo of Microsorum.

19 May 2011, NA Martin, Annual cycle: added photos of moths, larva and pupa. Recognition: added photos of moths and larvae. Host plants: added photo of Microsorum.